A DISORGANIZED AREA OF DISTURBED WEATHER...ASSOCIATED WITH A BROAD AREA OF LOW PRESSURE...HAS DEVELOPED A COUPLE HUNDRED MILES SOUTH OF THE GULF OF TEHUANTEPEC. SOME GRADUAL DEVELOPMENT OF THIS SYSTEM IS POSSIBLE AS IT MOVES SLOWLY TOWARD THE NORTHWEST DURING THE NEXT COUPLE OF DAYS.

And from the morning eastpac TWD:

...TROPICAL WAVES...
A TROPICAL WAVE IS ALONG 93W/94W TO THE S OF 14N AND HAS MOVED W AT 5-10 KT OVER THE PAST 24 HOURS. THE WAVE IS EMBEDDED WITHIN A BROAD AREA OF CYCLONIC TURNING IN THE LOW LEVELS WITH THE 1218 UTC QUIKSCAT PASS INDICATING TWO POSSIBLE SURFACE CIRCULATIONS NEAR 11N98W AND 11N93W. VISIBLE SATELLITE IMAGERY CONFIRMS THE EXISTENCE OF BOTH CENTERS. THE CENTER NEAR 11N98W IS ANALYZED AS A SURFACE LOW PRES 1007 MB. SCATTERED MODERATE TO STRONG CONVECTION IS SLOWLY ORGANIZING WITHIN THIS BROAD AREA OF CYCLONIC TURNING AND ALSO ALONG THE ITCZ BETWEEN 92W AND 101W.

I am so not good at trying to see these developing TC. Did bring up the sat loop, but even having it stare me right in the face, could not pick it up. It must be nudged into a tiny area of low shear.

I agree; the convection is consolidating. There are two separate areas competing against each other, however; one along 103W and the other closer to 97W. If that all consolidates or one takes hold, something should get going there. It'd be a mark for the GFS and the mesoscale models run off of it if so.

it's happening a little slower than GFS predicted, but 91E looks to be contracting into a single coherent low pressure area near 11n 101w. for some reason ssd doesn't have a rating on this area (a couple of too weak ratings from tuesday are all it's managed so far), but that should change shortly. i think we'll get another forecast cycle of just an outlook, but by the 8pm or maybe the 2am pdt intervals it might be marked up to a depression. exactly how this thing evolves can play heavily into what happens in the caribbean/gulf over the next few days--could easily draw a wash of westerly winds in and create a lot of convergence, and scramble the upper air flow up and leave a pocket or two of development-friendly areas in our basin.
as of right now, think this will be aletta late tomorrow or saturday, and that early next week it will be up thumping along the mexican riviera.
HF 2030z25may

I've been using the PSU site to look at models and they have one I have haven't seen before. The "WRF (experimental)" What is this model based on and is it any good? Is it the equivalent of the homegrown FSUMM5? It seems to develop 91E too. Thanks>>Adam

The WRF is the next generation in the line of mesoscale models. It's similar to the MM5 in many ways -- in fact one version of the internal WRF core is based largely off of the MM5 -- with some subtle differences. It's still under development, however. A specialized version -- the Hurricane WRF -- should be released soon and will include many features ideal for hurricane forecasting.

If/once this situation with FSU is resolved, you can expect that we will be running the WRF at least on a semi-regular basis at some point during the coming season.

Agree wholeheartedly with HF's assessment of this developing disturbance. It's got some semblance of an outflow jet to the north and northeast, but this feature is also leading to some weak-moderate shear over the storm. Nothing too big, however. The SSTs that it is near are really warm -- 30C -- but the waters along the coastline are a touch shallow. Nothing like what Adrian encountered last year, however. Some odd runs of the GFS wanted to take this toward the Isthmus of Tehuantepec; it could happen, but I don't think it's the most likely scenario. Further west is more likely. Figure it's got a fair shot at some intensification, outside shot at minimal hurricane intensity.

After last year, don't you feel that it's important to start this year's season in a certain frame of mind. That is, it is very necessary to be not too serious (seriously).

Thankfully, James Franklin, Senior Hurricane Specialist, has done just that.

I started noticing earlier in the week that Franklin was doing both the 4am and the 4pm TWO. I added a comment about it a couple days ago, on an email I sent, and he replied, in his typically dry and understated manner, "It's about time someone noticed that about the TWO's." But what I didn't notice until last night (insomnia struck again), was that the 10pm -- which comes out after midnight my time -- was also being written by him as well.

Of course the reason it is so important to be a little silly is to balance out what is always in the back of our minds, and what we can't ever quite forget, about why tropical weather is such a big deal: it poses such an extreme risk to life and property, and more so for parts of Central America. So, from the 10amTWO, I just wanted to post this as a reminder of what Stan did last year, and the posibility of the same type of danger so early in the 2006 season:

"EVEN IF A DEPRESSION DOES NOT FORM...HEAVY RAINS COULD SPREAD ACROSS PORTIONS OF SOUTHEASTERN MEXICO DURING THE NEXT COUPLE OF DAYS. THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES...ESPECIALLY IN MOUNTAINOUS TERRAIN."

this is one of those systems that i'd call a depression, but NHC makes that call and not me. it essentially meets the official definition, as is. the only fuzzy point would be 'organized convection'. it looks organized to a depression level to me.
the official guess is that shear will weaken on it some. SSTs ahead in its forecast movement region are above normal and more or less in the upper 80s. once the developmental feedback gets going on this sucker it may really get going... up to minimal hurricane strength like clark is saying. proximity to the coast and increased deep layer steering should start it moving nnw to n. not much threat of an atlantic crossover as any remnant circulation blown over the mountains would be in a stronger shear environment. seeing as we don't have a storm to track yet (officially) this is thinking too far ahead.
the pesky model-predicted atlantic system in the western caribbean from a few days ago isn't there in the newest runs. steering in the region ought to become more southerly later next week, and anything jammed up down there could come up. GFS has a baroclinic type feature from a tropical energy surge ahead of the deep trough progged to dig into the east by next weekend, so regardless the pattern could still spit something up from down there. more likely, though, that action will remain in the pacific into early june.
minor note that a deep layer cutoff low should be stuck out in the bermuda triangle region during next week, but models aren't showing it hybridizing or anything.
synoptic pattern and configuration of atmospheric features right now is a little like la nina, maybe as a residual effect of the la nina conditions that existed in the pacific over the winter. they do not usually favor early season atlantic activity. however, the atmosphere should adjust back to an ENSO neutral configuration as the la nina failed to launch. maybe something, unfortunately, like 2004-2005.
HF 0722z27may

I think it's really starting to get it's act together very quickly during the past few hours. It's much better looking right now then ever and it's not messy looking right now. If it continues doing this, it's 100% tropical depression and then tropical storm. A hurricane isn't out of the question either becuase the GFDL shows that. Hmm...

And...all is well in the hurricane forecasting world (no, I'm not going to explain that one).

Now, Ed, just indulge me, will ya?

Last year I went online in July to try to find information for my brother about Dennis, and ended up here, at CFHC. Never did I think that the rest of 2005 would be the "long strange trip" that it was.

Now, I'm here deliberately, happily, on my own, having (hopefully) learned a lot, and even though I'm still dealing with the aftermath of Katrina on my family and friends, being here, right at the start of a hurricane season, for the very first time, feels right. I'm still very unsure of my place in this new world, not being a met, but I'm on board, anyway!

* * * * * * *

Update -- the NRL designation has switched to NONAME. Not sure when that occured. It looks like convection tried to wrap around the west, then it was sheared away. But perhaps we will have the first named storm of the eastpac season, not too far away. A very recent quikscat (1707Z) shows some surface wind vectors that qualify, in a fairly well-defined LLC. However the descending scan shows much weaker surface winds.

Could someone with met experience explain the difference in the ascending and descending quikscat. I often see differences between the two views; is this due to the viewing angle?

aletta as entered a world that isn't fully ready to let it thrive. just like late yesterday the center of the storm has swirled out west of the main convective area, while the general motion of the storm has been hopscotching northeastward over the last day or two. with that jet still northwest of the storm i doubt this center will survive as is, and a new one will likely reform just as it already has twice, underneath the CDO. the current forecast philosophy looks about right, though i do think it will wander inland and die, rather than brush the coast and take off westward when the upper sw flow lets go and the ridging to the north strengthens. i don't think aletta will get stronger than about 50mph.
now, if the upper jet relaxes sooner, it'll probably start westward early and miss the coast. in that case it could get a little stronger.
there's a wave coming across panama/costa rica on the back side of aletta. if it rides up a little on the ITCZ there's a chance it will start festering behind the lead storm. models not too excited over this prospect as of now.
don't see the atlantic doing much for the next week or two.
HF 2322z27may

Indeed, A huge burst of deep convection has occurred during the past few hours. The main question is, will it make landfall? I think it will not and the NHC thinks that too right now. It's going to get afwully close to making landfall though.

Current 0445Z imagery is showing a nice, consolidated CDO. Dvorak T numbers haven't updated since 29/2345Z. At that time Aletta was holding a 2.5 intensity.
0445Z RBG shows a moderate amount of lightning in the CDO area. However, the WV image from the same time is showing a N to S elongated, double convective cluster, similar to a solid figure 8.
NW through SW convective band is disconnected from the main CDO, and appears as an outflow boundary. Possibly the "death outflow" in the storms dying stage.
The few, weak bands that are connected are in the NE through SE Quadrant.

Looks a little better this morning; it finally got out from under the jet and is not as sheared. It's in a nice little pocket. Looks like it'll become more organized today (convection is closer to the center) and tonight, and then into the shear and dry air, and that'll be it.

I'm really liking the longer sat loops -- I can sleep in and still see what you were looking at last night! :-)

* * * * * *

I learned something new with advisory #10A, not having watched the eastpac before -- apparently if there are no watches or warnings to be issued, then advisories are discontinued. That makes sense for the eastpac.

Danny was right...poof!...Aletta is so gone -- do you think I'll be able to remember what the "death outflow" looks like next time around? No convection even left now (image from around 0000Z attached), and the 11am PDT was the last advisory.

I learned the 'death outflow' from Jim Cantore. It works about 75% of the time or more.
The Death Outflow basically looks like the outflow you would see from any thunderstorm complex. A thin line of clouds/ light convection, detached from the parent cloud.
On the RGB satellite pic. It resembles a jellyfish or Portugese Man-O-War.
The word " poof" would be a good example to describe it. You'll know it when you see it.

Hey, I stand corrected. Well, that is, I noticed there was a 2pm PDT discussion (my web page had not refreshed the numbers earlier, I think, because I only saw discussion #10). So, maybe even though public advisories are no longer being issued, discussions and other parts of the "advisory" package still have to be issued...so, the TWO is correct. I'll have to get the specifics on this, to satisfy my curiosity.

* * * * * *

Well maybe everyone knew this but me, since I am so new to this, and have not ever looked at the eastpac before. The forecast advisory pkg is issued for eastpac storms, but the public advisory statement part is not always issued, only when the storms are approaching land. It makes sense that the storms are usually moving the opposite direction, out to sea.

TROPICAL STORM ALETTA IS ESTIMATED NEAR 15.9N 102.1W AT 2100 UTC. THIS POSITION IS ABOUT 120 MILES...195 KM...SOUTH OF
ZIHUATANEJO MEXICO. ALETTA IS MOVING W AT 5 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1004 MB. MAXIMUM SUSTAINED WIND SPEED IS 35 KT WITH GUSTS TO 45 KT.
SCATTERED MODERATE TO STRONG CONVECTION WITHIN 150 NM ONLY OVER SE QUADRANT.
SHEAR IS EXPECTED TO BRIEFLY WEAKEN AND STRENGTHEN AGAIN IN ABOUT 36 HOURS SO THE ADVISORY MENTIONS A SLIGHT INCREASE FOR A DAY OR SO...WITHIN A WEAKENING TREND THEREAFTER.
SEE LATEST NHC FORECAST/ADVISORY UNDER AWIPS/WMO HEADERS MIATCMEP1/WTPZ21 KNHC FOR MORE DETAILS.

Aletta looks worse then most tropical waves right now. It just died in a matter of hours with the NHC calling for some strengthening tonight. It went poof for sure and it's still a tropical storm!! I bet the NHC will call it a depression at the next issue and it weakening to nothing.

What was the reason it went poof tonight? The shear was keeping the system from gaining strength 2 days ago and then the shear weakening and so did aletta? I'm confused of why Aletta was alive during the high shear and then it went poof when the shear disappeared.

As of late last night. The presence of 2 Lows, one NW and one NE of Aletta, might have had something to do with it.
Both of the Lows were lower in pressure than Aletta. One of the Mets can tackle this question better.

Aletta was within 150 miles of shore last night. The waters there are shallow. That should make them a bit cooler. With less Oceanic Heat Content.

I learned more about the "death outflow." This stuff is so interesting.

It is surface outflow. So that means there is divergence at the surface, not convergence, like there should be, and so convection will collapse. And this part I am not so clear about but it is possibly caused by dry air being pulled in probably at the mid-level.

That's largely it -- tropical convection results from a nearly moist profile and has a natural resilience to downdrafts. But, bring in some dry air in the mid-levels and you create conditions favorable for strong evaporative cooling as well as the development of downdrafts. Downdrafts can help develop convection elsewhere, but more specifically they mark the collapse of the pre-existing convection. That's not good for a tropical cyclone.

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